A nerve block can be used to treat a variety of pain, such as chronic pain, acute pain, or the pain resulting from a surgical procedure. The nerve block can be established by delivering a local anesthetic to a nerve or ganglia to block a specific nerve distribution to reduce or eliminate pain in a specific portion of the anatomy. The anesthetic is typically delivered to the nerve by needle injection or catheter infusion. One drawback with this delivery method is that the anesthetic may diffuse rapidly into the surrounding tissue and into the vasculature, which can reduce the effectiveness of the anesthetic at the target site and cause adverse side effects.
An alternative technique for establishing a nerve block is via electrical stimulation of the nerve or ganglia. However, such electrical stimulation typically requires a relatively high level of power in order to block the nerve, which results in a rapid discharge of a battery powered device.
Accordingly, it would be desirable to provide a system and method for establishing a nerve block in an efficient and effective manner.
Furthermore, in any implanted device including circuitry it may be useful or necessary to include some form of time keeping or clocking function. A common example of such an implantable device is a pacemaker which must keep time for each beat of the patient's heart. Other examples include an implantable neurostimulation device that periodically outputs some form of stimuli to address some underlying disorder (e.g. chronic pain). Nerve blocking implants are an example of such an implantable neurostimulation device. A clocking function may be necessary or helpful in these implantable devices because stimulating output from these devices may occur periodically and/or regularly over some period of time. Thus, these devices may utilize a clocking function to keep track of when a simulating session has occurred or will occur, and particularly clocks that are able to determine the time of day and/or date.
In designing the clocking function within implantable devices, certain considerations should be addressed. While a high level of accuracy is always desirable, there may be certain drawbacks associated with having a clocking assembly with high accuracy. While highly accurate main clocking systems are able to synchronize and coordinate various circuit and component operations, a major drawback is that they operate on a relatively large current and thus consume a lot of power. In addition, high accuracy clocking mechanism such as piezoelectric crystals are more expensive and more prone to damage. Because implantable devices are powered by batteries with a finite life and more recently through wireless charging, it is desirable to have a clocking mechanism for an implantable device that is able to maintain accuracy but does not draw a lot of power and is fairly inexpensive. Thus, it would be advantageous to have a clocking system that incorporated the low power consumption characteristics of a less accurate clocking module but still maintain a certain level of clocking accuracy.